This invention relates to apparatus for sensing the presence of oil above a certain percentage in water, and is intended primarily for use in industrial plants, oil tank farms and other installations wherein it is necessary to detect the presence of oil in water above a certain percentage, (i.e. number of parts per million). Applications include preventing the recycling of oil-polluted water from an industrial process, preventing the discharge of oil-pulluted yard area run-off water into lakes, streams, etc., providing a reliably sensitive means for detecting oil leaks and spills, and similar uses. As herein illustratively described, the invention is advantageously embodied in certain oil/water separating apparatus of the nature disclosed in copending patent application Ser. No. 566,926, filed Apr. 10, 1975, the teachings of which are hereby incorporated herein by this reference. However, it will be recognized that the present invention has other applications as well and that the same may be practiced in varying forms without departing from the essential features involved.
There are many important applications in which surface runoff water or industrial process waste or recycling water may become contaminated with oil. In most situations as long as the oil occurs merely in trace amounts (i.e., such as a few parts per million), no responsive or corrective action is required. In many of these cases continuous or intermittent samplings of water being recycled or discharged may be an adequate safeguard without necessity of passing all of the water through a separator to assure removal of excess oil. The present invention is useful in detecting or responding to an excessive proportion of oil in samplings of water. However it is equally effective in conjunction with the continuous or intermittent operation of an oil/water separator routinely processing all of the discharging or recycling water in a purification system.
For example, in the case of an oil tank farm, such as at a tanker truck terminal, in which oil is routinely pumped into and from storage tanks, there are bound to be minor amounts of oil spillage on aprons and open yard areas from time to time. A major leak or spill is also possible. Rainwater and other surface run-off water collecting in or passing through such a facility should therefore be processed or at least sampled and tested as a matter of course before it is discharged into a storm sewer or directly into open bodies of water. Typically, drainage and run-off water to be discharged is first collected in a sump. By intermittently or continuously testing this water for percentage of oil the present invention affords a sensitive means of automatically sounding an alarm or taking other remedial measures should excess oil occur, such as if one of the main storage tanks spring a leak. In addition this invention provides a means to process water to separate out the oil while reliably and accurately sensing an abnormally high proportion of oil present in the water from any source or cause.
It is also an object hereof to provide a means for sensitively detecting the presence of oil in water above a certain proportion during and in conjunction with oil/water separation processing that is effective whether the oil occurs in an emulsified state, a stratified or coalesced state, or both.
Still another object hereof is to devise a simple, sensitive and reliably accurate oil proportion detector operable in a separator system of the nature indicated, which adds minimal cost or complexity to the system and which does not interfere with normal operation thereof. A related object is to provide such a detector that functions consistently under dynamic operating conditions whether the separator is operating on a continuous or intermittent basis. Moreover, such detection apparatus provides substantially immediate response when percentage of oil in the mixture increases above a predetermined value, and it requires no delicate calibration adjustments, and no special primary or preconditioning for start-up.
A further object hereof is to provide a combined oil/water separating and oil proportion excess sensing system with the capability of accommodating or disregarding momentary oil proportion excesses. A related object is to also provide in such a system the capability of processing (i.e., separating) oil/water mixture in normal manner while oil percentage remains below a certain value and of shutting down automatically when it exceeds the oil volumetric rate handling capacity of the system.